1. Field of Invention
This invention relates to artificial mineralization of dental plaque, a composition and an aqueous solution for carrying out such mineralization.
2. Description of the Prior Art
It is known that calcium and phosphate concentrations in dental plaque vary from person to person and from site to site within the mouth. However plaque calcium and phosphate variations appear to be confined within certain limits. Fluoride concentrations within plaque are less closely controlled.
There is good evidence to suggest that these natural variations in plaque minerals are associated with variations in caries susceptibility. Theoretical considerations indicate that high plaque Ca and inorganic phosphate (P.sub.i) levels will lower the `critical pH`, the pH which plaque must reach before it becomes unsaturated with respect to biological apatite, and enamel dissolution commences (Dawes et al., Archs Oral Biol. 7: 161-172 (1962)). In addition, higher concentrations of P.sub.i may increase the buffering action of plaque and may inhibit acid production by certain plaque bacteria (Brown et al., Archs Oral Biol. 22: 521-524 (1977)). Increasing concentrations of plaque F may also be expected to have an increasing caries-protective effect because of this ion's inhibition of microbial glycolysis (Jenkins, Archs Oral Biol. 1: 33-41 (1959)). Thus, it is likely that the higher the concentration of Ca, P.sub.i and F in plaque, the greater will be the protection afforded.
Apart from these theoretical aspects, a protective role for plaque mineral ions is supported by a variety of clinical and experimental observations. Dental calculus, which may be regarded as plaque having a very high concentration of mineral, has long been associated with immunity to caries (Gottlieb: Dental Caries p.100 (Lea & Febiger, Philadelphia 1947)).
In plaque having insufficient mineral to be regarded as calculus, increased levels of calcium and phosphate have also been associated with increased resistance to caries. Ashley and Wilson (Br. Dent. J. 142: 85-91 (1977)) have found an inverse relationship between the levels of Ca, P.sub.i and organic phosphate (P.sub.O) in plaque and the number of tooth surfaces becoming decayed or filled over the first 2 years of a 3-year longitudinal study.
Likewise, clinical studies show that F in plaque tends to protect the enamel against dental caries. The plaque F concentration of children has been inversely related to their individual caries experience (Agus et al, Community Dent. Oral Epidemiol. 4: 210-214 (1976)) and to their number of caries-free teeth (Dental Plaque, p.p. 171-178 (Livingstone, Edinburgh, 1970)).
It is an object of this invention to go some way towards achieving higher concentrations of Ca, P.sub.i and F in plaque or at least to provide the public with a useful choice.